The EU Bioeconomy Strategy aims to support the sustainable growth and development of the EU bio-based sectors while creating jobs, innovation and services. Despite the recognized potential of the algae biomass value chain, significant knowledge gaps still exist regarding the dimension, capability, organization and structure of the algae production in Europe. This study presents and analyses the results of a comprehensive mapping and detailed characterization of the algae production at the European scale, encompassing macroalgae, microalgae, and the cyanobacteria Spirulina. This work mapped 447 algae and Spirulina production units spread between 23 countries, which represents an important addition to the reported number of algae producing countries. More than 50% of these companies produce microalgae and/or Spirulina. Macroalgae production is still depending on harvesting from wild stocks (68% of the macroalgae producing units) but macroalgae aquaculture (land-based and at sea) is developing in several countries in Europe currently representing 32% of the macroalgae production units. France, Ireland, and Spain are the top 3 countries in number of macroalgae production units while Germany, Spain, and Italy stand for the top 3 for microalgae. Spirulina producers are predominantly located in France, Italy, Germany, and Spain. Algae and Spirulina biomass is directed primarily for food and food-related applications including the extraction of high-value products for food supplements and nutraceuticals. Algae production in Europe remains limited by a series of technological, regulatory and market-related barriers. Yet, the results of this study emphasize that the European algae sector has a considerable potential for sustainable development as long as the acknowledged economic, social and environmental challenges are addressed.

Trophic spectra represent the distribution of biomass, abundance, or catch by trophic level, and may be used as indicators of the trophic structure and functioning of aquatic ecosystems in a fisheries context. As a theoretical background, we present a simple ecosystem model of biomass flow reflecting predation and ontogenetic processes. Biomass trophic spectrum of total biomass can be modelled as the result of three major factors and processes: trophic efficiency, transfer kinetics, and extent of top-down control. In the simulations, changes in the spectrum highlight fishing impacts on trophic structure and reveal some functional characteristics of the underlying ecosystem. As examples of potential applications, three case studies of trophic spectra are presented. Catch trophic spectra allow description of structural differences among European fishing areas and periods. Abundance trophic spectra of coral-reef fish assemblages display different trophic signatures, characterizing different reef habitats in New Caledonia and highlighting fishing effects in a marine protected area context. Biomass trophic spectra of demersal resources off Northwest Africa show a shift in ecosystem structure that can be attributed to the rapid increase in fishing pressure during the past few decades. Off Senegal, total biomass remained fairly constant, suggesting a strong top-down control linked to fisheries targeting high trophic level species. Off Guinea, exploitation rates are spread over a wider range of trophic levels, and the total biomass of demersal resources tended to decrease. The trophic spectrum is concluded to be a useful indicator describing and comparing systems in time and space, detecting phase shifts linked to natural or anthropogenic perturbations, and revealing differences in ecosystem functioning.

West African marine ecosystems are very productive and sustain important fisheries that have developed rapidly in the last decades. The analysis of the fishing impact on exploited resources is usually conducted through single-species assessments. In this study, we propose a complementary approach that enables to account for some ecosystem effects of fishing. In Guinea and Senegal, fisheries have developed relatively recently and at the same time, the collection of landings and surveys data has been carried out. In consequence, the data collection extends from a period where stocks could be considered as non exploited to a situation of overexploitation. This case study is analysed in order to detect shifts in the ecosystem structure in response to increasing fishing pressure. To this aim, trophic spectra and long time series of mean trophic level are examined for demersal fish communities. Trophic spectra display either the distribution of the demersal community biomass or the commercial catches according to trophic level classes. Some substantial and statistically significant changes in the trophic structure of the Senegal and Guinea ecosystems were observed. In particular, the biomass of the high trophic levels decreased whereas the lower trophic levels displayed a relative stability or an increase. This could be linked to a "top-down" fishing effect due to a release of predation on the lower trophic levels of the demersal fish community. In Senegal, the mean trophic level decreased significantly for both the catches and the demersal community biomass. Such a decrease was also observed for the coastal demersal biomass in Guinea. This showed that fishing activities had an impact on the trophic structure of the ecosystem, and a "fishing down marine food web" effect was shown in West Africa for the first time.

Abstract:Worldwide kelp forests have been the fields of several studies concerning ecosystems dysfunction in the past decades. Multifactorial kelp threats have been described and include deforestation due to human impact, cascading effect and climate change. Here, we compared community and trophic structure in two contrasting kelp forests off the coasts of Brittany. One has been harvested five years before sampling and shelters abundant omnivorous predators, nearly absent from the other, which has been treated as preserved from kelp harvest. δ 15 N analyses conducted on the overall communities were linked to the tropho-functional structure of different strata featuring these forests (stipe and holdfast of canopy kelp and rock). Our results yielded site-to-site differences of community and tropho-functional structures across kelp strata, particularly contrasting in terms of biomass on the understorey. Likewise, isotope analyses inferred the top trophic position of Marthasterias glacialis and Echinus esculentus which may be considered as strong interactors in the sub-canopy. Our intention is to discuss these patterns and propose a series of probable and testable alternative hypotheses to explain them. For instance, we propose that differences of trophic structure and functioning result from confounded effects of contrasting wave dissipation depending on kelp size-density structure and community cascading involving these omnivorous predators. Given the species diversity and complexity of food web highlighted in these habitats, we call for further comprehensive research about the overall strata and tropho-functional groups for conservation management in kelp forests.

Large, P. A., Diez, G., Drewery, J., Laurans, M., Pilling, G. M., Reid, D. G., Reinert, J., South, A. B., and Vinnichenko, V. I. 2010. Spatial and temporal distribution of spawning aggregations of blue ling (Molva dypterygia) west and northwest of the British Isles. – ICES Journal of Marine Science, 67: 494–501. Fisheries on blue ling in ICES Areas Vb, VI, VII, and XIIb have mostly targeted spawning aggregations. ICES has repeatedly advised that blue ling are susceptible to sequential depletion of spawning aggregations and that closed areas to protect spawning aggregations should be maintained and expanded where appropriate. Information from a range of sources, including fishers, is analysed, and five main spawning areas are identified: (i) along the continental slope northwest of Scotland (ICES Division VIa); (ii) on, around, and northwest of Rosemary Bank (VIa); (iii) on the southern and southwestern margins of Lousy Bank (Vb); (iv) on the northeastern margins of Hatton Bank (VIb); and (v) along the eastern and southern margins of Hatton Bank (VIb). From the information available, it is suggested that, for management purposes, peak spawning be considered to take place at depths of 730–1100 m between March and May inclusive in VIa and Vb, and during March and April in VIb. Based largely on this information, the European Commission (EC) introduced in 2009 protection areas for spawning aggregations of southern blue ling in European Union (EU) waters within ICES Division VIa.

International audienceThe relative contribution of kelps and other food sources to the diet of consumers in shallow coastal communities has been hotly debated in recent years. It has been suggested that considering proxies instead of phytoplankton isotopic signatures can lead to an overestimation of kelp contribution through isotopic mixing models. We analysed spatial patterns in carbon isotopic ratios of the dominant primary sources and consumers at two subtidal sites in Brittany (France) prior to the anticipated 2011 phytoplankton bloom to determine which of kelp and phytoplankton is the dominant food source in Laminaria hyperborea forests. We found simultaneous spatial variations for consumers, kelps and deposited particulate organic matter, suggesting that kelp-derived organic matter is a key component of associated food webs for at least part of the year

a b s t r a c t a r t i c l e i n f o Keywords: Laminaria Lidar Acoustic imagery Zero-inflated model Habitat mapping Spatial managementThe Molène Archipelago in Brittany (France) hosts one of the largest kelp forests in Europe. Beyond their recognized ecological importance as an essential habitat and food for a variety of marine species, kelp also contributes towards regional economies by means of the alginate industry. Thousands of tons of kelp are collected each year for the needs of the chemical and food industries. Kelp harvesting in Brittany mainly concerns two species, Laminaria digitata (59,000 t) and Laminaria hyperborea (24,000 t), that, together, represent approximately 95% of the national landings. Estimating the available standing stock and its distribution is a clear need for providing appropriate and sustainable management measures. Prior to estimating the spatial distribution of biomasses, we produced a detailed seabed topography map with accurate hard substrate delineation thanks to surveys and appropriate processing of airborne optical and acoustic imaging. Habitat suitability models of presence-absence and biomass were then developed for each species by relating in situ observations from underwater video and sampling to the many biotic and abiotic factors that may govern kelp species distribution. Our statistical approach combining generalized additive models (GAM) in a delta approach also provided spatial uncertainty associated with each prediction to help management decisions. This study confirmed that the adopted strategy, based on an integrated approach, enhanced knowledge on kelp biomass distributions in the Molène Archipelago and provided a promising direct link between research and management. Indeed, the high resolution topography and hard substrate maps produced for the study greatly improved knowledge on the sea bottom of the area. This was also of major importance for an accurate mapping of kelp distribution. The quality of the habitat suitability models was verified with fishing effort data (RECOPESCA program) and confirmed by local managers and kelp harvesters. Based on the biomass maps produced and their associated confidence intervals, we proposed more precise management rules than those already in use for both L. digitata and L. hyperborea. Our mapping approach is a first step towards sustainable kelp species management in the area. Introducing higher resolution environmental variables and population dynamics would help interannual management.

This paper examines the fishing of blackfin tuna (Thunnus atlanticus) around Fish Aggregating Devices (FADs) in Martinique (French West Indies). It is based on the compared analysis of catches from monthly experimental fishing surveys and sampling of commercial landings. The data collected in these two different ways allowed comparison of blackfin tuna length frequencies. A large part of the commercial landings were made up of young immature tuna with a fork length of less than 40 cm, whereas the experimental longline catches were mainly made up of fish with a fork length ranging between 55 and 75 cm. We give evidence that these discrepancies were mostly due to the fishing technique used. Indeed, contrarily to the experimental surveys, Martinican fishermen only fish during daytime and usually on the surface by trolling. This way, fishermen do not have access to the largest fish, which are found deeper. Our results suggested that a new fishing technique such as vertical longlining, could improve commercial catches of big blackfin tuna under FADs.